The field of the disclosure relates generally to electric motor controllers, and more specifically to methods and a controller for reducing size and costs of motor controllers for electric motors.
Devices commonly known as electronic motor controllers are utilized to control the operation of certain electric motors. At least some known motor controllers have attempted to reduce cost and save resources by replacing large-capacity smoothing capacitors with small-capacity capacitors. Because of the small-capacity capacitor, a rectified input voltage to be applied to an inverter is unable to be properly smoothed and has a pulsating waveform. The voltage of the pulsating waveform has a frequency about twice that of an output voltage of an alternating current (AC) power supply to which it is connected.
When using electric motor controllers, a sinusoidal input current may be sacrificed, which can lead to a poor power factor for the electric motor. Active power factor correction devices are known to correct the power factor, but are typically large in size and are often costly. Alternatively, at least some known motor controllers apply a torque command to be synchronous with line input voltage to correct poor power factor. However, measuring line input voltage necessitates an additional isolated voltage sensor, which increases the system cost.